This invention relates to the recording of chemical activities, and more particularly to apparatus for photographically recording the radiation emitted as a result of an immunological or other chemical reaction thereon, for subsequent measurement to determine the extent of the reaction.
A variety of chemical reactions may be evaluated and recorded photographically by radiation emitted directly or indirectly from the reaction, including reactions in the field of immunology. The background of this invention will be discussed in the context of immunology, although the principles are equally applicable in other fields.
One aspect of the field of immunology involves the testing of persons to determine their allergic sensitivity to various substances commonly encountered, such as pollen or animal fur. In an early test to determine sensitivity to various allergens, a sample of the suspected allergen was placed on a patch and the patch was then placed in contact with the person's skin. After several days, the patch was removed and the skin examined to determine the presence of any allergic reaction. Another approach was to inject test materials under the person's skin. These qualitative tests are subject to numerous inaccuracies, are costly and inconvenient for the user and the patient, and at most only one or a few suspected allergens can be evaluated simultaneously.
In a new test for determining allergic reactions, other immunological reactions, or other microbiological interactions, an insoluble carrier coated with a known quantity of a single antigen such as that found in an allergen can be exposed to, and incubated in, a sample of blood withdrawn from the body. If the person is allergic to the particular antigen, a measurable binding reaction occurs during the incubation. A variety of techniques can then be utilized to indicate the extent of such reaction, and one such technique involves the use of a radioimmunoassay, in which the carrier is incubated with a liquid containing radioactively tagged molecules that bind to any serum antibody previously bound to the antigen coated carrier during the incubation.
Once the molecules are tagged, it is necessary that their number be measured in some fashion to determine the extent of the reaction. One approach is to expose photographic film directly to the radioactive portion of the carrier, but this approach requires long exposure times. Alternatively, the gamma radiation produced from the radioactive carriers may be used to produce visible radiation by autoradiographic techniques wherein light is emitted from an intensifying screen under stimulation by the gamma radiation.
While the principles of autoradiography are well known, there has not been provided a convenient apparatus whereby users may prepare photographs using conventional film by autoradiographic techniques, nor has there been provided an apparatus which is portable and self-contained whereby such photographs may be prepared without the need of auxiliary apparatus or a photographic laboratory. Further, such a portable and self-contained apparatus would allow the autoradiographic exposure to be conveniently made at reduced temperatures, which would further reduce exposure times.
Accordingly, there has been a need for a self-contained, portable apparatus for preparing photographic records of the extent of chemical reaction using radiation emitted as a result of the reaction. Such apparatus is particularly desirable in fields such as immunology wherein radioactively tagged reactions on a substrate must be recorded for subsequent measurement and evaluation. The present invention fulfills this need, and further provides related advantages.